1. Field of the Invention
This invention relates to improvements in automatic injectors. Additional embodiments include a sharps protector that is manually or automatically operable.
2. Description of the Prior Art
Military personnel under chemical attack are trained to use automatic injectors when an injection is needed on an emergency basis in the field where medical personnel are not available to perform the injection. Civilians or military personnel who are allergic to bee or wasp stings, and the like, may use them when there is no access to emergency medical service (EMS) personnel or insufficient time to travel to a medical facility. Passenger aircraft are often equipped with automatic injectors as well for use when a passenger has a food allergy that creates a medical emergency. Most emergency medical vehicles also carry automatic injectors for the emergency treatment of allergic reactions. There are other uses for automatic injectors as well.
The automatic injector disclosed in expired U.S. Pat. No. 4,031,893, commercially known as the EpiPen(copyright) epinephrine auto-injector, invented primarily by the present inventor, has been in widespread use for more than twenty years. The military version thereof is known as the Pralidoxime ComboPen. The user grasps an outer cylindrical sleeve of the injector and delivers the leading end of the device to the injection site with a force sufficient to cause release of a spring-loaded needle. More specifically, when the device is ready to be used, the outer cylindrical sleeve trails an inner cylinder from which the needle or cannula extends so that when the leading end of the outer cylindrical sleeve hits the user""s skin, the movement of the trailing end of the outer cylindrical sleeve releases a spring and the spring drives a piston that pushes liquid medicament out of a cartridge and Into the user""s tissue through the cannula.
The ""893 device fulfilled the needs of its (pre-AIDS) time, but it includes no means for covering the sharp cannula after it has been deployed. Thus, the exposed cannula represents a hazard to those who come into contact with it after it has been withdrawn from the tissue of the user. Nor is it a simple matter to retrofit the cannula with a sharps protector because there is insufficient space within which to mount a sharps protector.
The ""893 device also uses a relatively large amount of plastic material in its construction due to the aforesaid outer cylindrical sleeve.
Another drawback of the ""893 device is that the user must aim at and hit the desired point of injection in one motion. Impact of the device against the user""s body triggers extension of the cannula by causing the release of a loaded piston biasing means if the device works in accordance with its design.
Premature deployment is therefore a problem. For example, the cannula may deploy when the device is placed on any site with slight pressure or when brushed against a surface such as a wrinkle in a pair of trousers. Deformed or misaligned parts may cause such unwanted premature deployment. Such premature activation, caused by the inadvertent application of a slight amount of pressure, is clearly unwanted.
Accordingly, there is a need for an improved automatic injector having a design that reduces the chances of a premature cannula deployment.
There are also a number of factors that can result in a failure of the cannula to deploy properly. For example, the cannula may fail to properly deploy if the auto-injector spring is weak, if the cannula is occluded, if a glass medicament-containing ampule breaks, if the piston sticks to the interior surface of the glass walls of the cartridge holder sleeve, if the device otherwise jams due to a parts misalignment, or the like.
A need therefore exists for an automatic injector having a design that reduces the chances of an improper cannula deployment.
Astronaut suits and other special clothing items include a special (self-sealing) area of the clothing designed to accept a cannula so that an emergency injection may be performed in the absence of a need to remove the clothing. The special area is small and not easy to hit when performing an emergency injection.
Thus there is a need for an automatic injector that would enable the user to position the leading end of the device in juxtaposition with an intended injection site before the needle is triggered.
Moreover, an automatic injector having means for shielding the deployed cannula is needed.
A good design also minimizes the use of natural resources, especially in devices that are used only once and discarded or re-cycled.
A need therefore exists for an automatic injector formed of less material than the automatic injectors of the prior art.
The medicament in an automatic injector may become cloudy due to age or some other cause. it may even leak out of the automatic injector if the ampule that contains such medicament has been damaged. When cloudy or discolored in any way, or if not present in its full effective quantity, the efficacy of the medicament is in doubt. Accordingly, pre-injection visual inspection of the medicament is required to ascertain whether or not it is present and suitable for use. Some of the known automatic injectors such as the EpiPen(copyright) have somewhat clear, semi-transparent parts that enable visual inspection of the medicament, but there are three layers of said parts (an outer cylindrical sleeve, a cartridge holder sleeve, and the medicament-containing ampoule). The outer cylindrical sleeve and the cartridge holder sleeve are formed of natural plastic and thus are semi-transparent. The ampoule is formed of clear glass. Thus, if either of the outer two parts become cloudy or otherwise lose at least some degree of transparency, visual inspection of the medicament is hindered.
Thus, there is a need for an automatic injector made of fewer parts so that pre-injection visual inspection of medicament does not require looking through three layers of parts.
An automatic injector can also fail because the medicament contained therewithin may fail to reach the tissue of the patient in whole or in part due to various mechanical malfunctions of the device. For example, it is possible for the cannula to deploy but for none of the medicament, or just a fraction thereof, to actually flow through the cannula into the patient""s tissue.
Accordingly, there is a need for an automatic injector made of fewer parts so that post-injection visual inspection of medicament does not require looking through three layers of parts.
From a mechanical standpoint, the more parts a device has, the greater are the chances for a malfunction.
Thus there is also a need for an automatic injector having fewer parts to increase its reliability of operation.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The long-standing but heretofore unfulfilled need for an automatic injector that is constructed of less materials, that has fewer parts, that may be positioned at a preselected location prior to release of the cannula, that provides sharps protection, and that otherwise advances the art is now met by a new, useful, and nonobvious invention.
A cartridge holder sleeve has a lumen that slideably receives a cartridge, a piston, a spring holder, and an inner gun sleeve. The cartridge is adapted to hold a liquid medicament. A cannula hub is mounted to a leading end of the cartridge, and a cannula is mounted to a leading end of the cannula hub. The piston is disposed in trailing relation to the cartridge and the spring holder is disposed in trailing relation to the piston.
A first diameter-reducing shoulder is formed in the cartridge holder sleeve near a leading end thereof. Accordingly, a reduced diameter section of said cartridge holder sleeve is formed in leading relation to said first diameter-reducing shoulder.
A spring-retaining shoulder is formed in the spring holder near a leading end thereof. The spring holder further includes a plurality of longitudinally extending parallel legs that extend in trailing relation to the shoulder.
A leading end of the inner gun sleeve is positioned within the lumen and a trailing end is positioned external to the lumen. In some embodiments, a truncate outer gun sleeve engages the trailing end of the inner gun sleeve. A safety cap is mounted to the outer gun sleeve, and said safety cap includes a safety pin that extends through a central aperture formed in the outer gun sleeve into a space surrounded by the parallel legs of the spring holder.
A piston biasing means under compression has a leading end disposed in abutting relation to the spring-retaining shoulder of the spring holder and a trailing end disposed in abutting relation to a trailing end of the inner gun sleeve. The trailing end of the inner gun sleeve is adapted to releasably engage the respective trailing ends of the parallel legs of the spring holder.
When the safety cap and hence the safety pin are removed, manual pressure applied against the outer gun sleeve in a trailing-to-leading direction effects radially inward travel of the parallel legs of the spring holder, thereby releasing the piston biasing means and driving the cannula into the tissue of the user.
The cannula, cartridge, piston, and spring holder are positioned within the lumen of the cartridge sleeve holder, toward the trailing end thereof in a retracted position, when the piston biasing means is under compression. Said parts slide abruptly toward the leading end of the lumen when the piston biasing means unloads. The cannula extends out of the lumen in leading relation to the leading end of the cartridge sleeve holder when the piston biasing means is in repose, i.e., not under compression.
In a first embodiment, a manually operated releasing means disengages the trailing end of the spring holder from the trailing end of the inner gun sleeve so that the piston biasing means unloads when the releasing means is activated. The structure of the first embodiment eliminates the outer cylindrical sleeve of the automatic injector disclosed in the above-mentioned expired patent.
In a second embodiment, a sharps protector is mounted to the cartridge holder sleeve on the reduced-diameter section thereof.
The sharps protector has a first, retracted position where a leading end of the sharps protector is substantially co-extensive with a leading end of the cannula when the cannula is in a retracted position. The sharps protector has a second, extended position where a leading end of the sharps protector is substantially co-extensive with a leading end of the cannula when the cannula is in an extended position.
A user of the automatic injector manually displaces the sharps protector from the first, retracted position to the second, extended position after the release means has been activated.
More particularly, an annular detent means is formed in a trailing end of the manually operated sharps protector. A first annular recess is formed in the reduced diameter part of the cartridge holder sleeve, and the first annular recess receives the annular detent means when the sharps protector is in its retracted configuration. A second annular recess is formed in said reduced diameter part of the cartridge holder sleeve in leading relation to the first annular recess. The second annular recess receives the annular detent means when the sharps protector is manually displaced into its extended configuration.
In a third embodiment, a second diameter-reducing annular shoulder is formed in the reduced diameter section of the cartridge holder sleeve in leading relation to the first diameter-reducing shoulder and a diameter-reducing taper is formed in the reduced diameter section of the cartridge holder sleeve in leading relation to the second diameter-reducing shoulder. The second diameter-reducing shoulder provides a stop means for the trailing end of an internally mounted sharps protector biasing means, which may take the form of a coil spring, for automatically deploying the sharps protector.
The sharps protector biasing means has a lumen that receives the downwardly-tapered leading end of the cartridge holder sleeve. The sharps protector biasing means has a trailing end that abuts the second diameter-reducing shoulder and a leading end that abuts the leading end of the sharps protector, internally thereof.
In the third embodiment; a first latch means, formed of a pair of diametrically opposed first latch members, is formed in a trailing end of the sharps protector and is separated from the sharps protector along a parting line at a leading end and opposite sides of each first latch member. A trailing end of each first latch member forms a living hinge with the sharps protector and the leading end of each first latch member extends into a first catch means to prevent unloading of the sharps protector biasing means. The first catch means includes a pair of diametrically opposed slots or catch members formed in the reduced diameter section of the cartridge holder sleeve.
Accordingly, retraction of the leading end of each first latch member from its associated first catch member enables unloading of the sharps protector biasing means and deployment of the sharps protector to its fully extended position where the deployed cannula is fully housed therewithin.
A pair of diametrically opposed accommodation slots is formed in the sharps protector in spaced apart, leading relation to the first catch members. A stop means includes a pair of diametrically opposed stop members. Each stop member is separated from the sharps protector along a parting line at a trailing end and opposite sides of each stop member, leaving a living hinge at the leading end of each stop member. The trailing end of each stop member extends into its associated accommodation slot when the sharps protector biasing means is under load and the sharps protector is in its retracted position. The trailing end of each stop member extends into its associated second catch member when the sharps protector biasing means is unloaded and the sharps protector is in its deployed position, thereby preventing displacement of the sharps protector in a leading-to-trailing direction.
A pair of diametrically opposed elongate guide slots are also formed in the reduced diameter section of the cartridge holder sleeve. A pair of diametrically opposed detent means is formed in the trailing end of the sharps protector. Each detent means slideably engages an associated guide slot.
In a fourth embodiment, the trailing end of an externally mounted sharps protector biasing means abuts the first diameter-reducing annular shoulder and the leading end of the externally mounted sharps protector biasing means abuts the trailing end of the sharps protector. The arrangement of latch members, catch members, stop members, and detents that control operation of the third embodiment also forms a part of the fourth embodiment.
An important object of this invention is to improve the design and hence lower the cost of conventional automatic injectors by substantially reducing the amount of materials used to make them.
Another important object of this invention is to provide an automatic injector having manually deployable means for covering a deployed cannula.
Still another important object is to provide an automatic injector having automatically deployable means for covering a deployed cannula.
Yet another object is to provide different embodiments of the automatic injector so that in a first embodiment the cannula may be placed into position with an injection site prior to activation of the cannula extending means and so that in a second embodiment the act of delivering the leading end of the auto injector to the injection site results in automatic deployment of the cannula.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.